Improve hacking.md

- Refer to current version in readme
- Split into flakes and non-flakes section
- Change order to move nix-build to the end, since people often start
  with it in the beginning.
- Use proper "Note" syntax
- Add notes about editor integration
- Move information about target platforms and stdenvs into separate
  sections

Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Co-authored-by: Alexander Bantyev <alexander.bantyev@tweag.io>
Co-authored-by: Théophane Hufschmitt <theophane.hufschmitt@tweag.io>

flake.nix

@@ -701,7 +701,10 @@
 
             outputs = [ "out" "dev" "doc" ];
 
-            nativeBuildInputs = nativeBuildDeps ++ [ clang-tools bear ];
+            nativeBuildInputs = nativeBuildDeps
+                                ++ (lib.optionals
+                                      nixpkgsFor.${system}.${stdenv}.cc.isClang
+                                      [ bear clang-tools ]);
             buildInputs = buildDeps ++ propagatedDeps ++ awsDeps;
 
             inherit configureFlags;